Field of the Invention
Embodiments of the present invention generally relate to pressure-sensitive digital input systems and, more particularly, to a method and apparatus for filtering pressure data from a pressure-sensitive device.
Description of the Related Art
Touchscreen devices allow users to navigate their computer devices with a touch of a finger or stylus on the touchscreen. The device reads input made by the contact of the finger or stylus and the screen. These devices have evolved to read strokes made by the finger or stylus on the screen and mimic these strokes graphically on the screen. Drawing tablets are computer input devices that allow users to hand-draw images and graphics on the tablet similar to how one would draw with a pencil on paper. Typically, a user draws with a stylus on the drawing tablet. The tablet is like a digital canvas where the motion of the stylus is reproduced digitally on a computer display. Architects often use tablets for architectural drafting, while artists commonly use tablets for artistic renderings. As such, precision and accuracy are important.
However, the raw pressure data from the stylus on a tablet device can be overly-sensitive or not sensitive enough for use in drawing variable-width vector strokes in applications such as ADOBE® Ideas (available from Adobe Systems, Inc. of San Jose, Calif.). This causes an abrupt change in the width of the strokes far more rapidly than a user may desire. Further, if the user selects a larger brush stroke width, the problem is more pronounced. If the user decreases pressure on the stylus, the stylus sometimes interprets this incorrectly as if the user has lifted the stylus from the tablet. As a result the system causes the stroke to end before the user actually intends for it to do so.
Therefore, there is a need for a method and apparatus for filtering pressure data from a pressure-sensitive device.